Abstract: The main objective of this study was to improve the mechanical properties of zein films by glycosylation for producing plant-derived capsule shells. The results showed that zein, which was extracted with 70% ethanol, was the amino donor of glycosylation by amino acid analysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimal conditions were determined as follows: ratio between zein and maltose syrup (MS), 11:1; pH, 9; ultrasonic power, 400 W; and time, 15 min. The tensile strength (TS) of the films produced under these conditions was 9.22 MPa, which was increased by about 2-fold compared with that (4.2 MPa) of unmodified zein films, and the degree of glycosylation (DG) was 34.96%. The formation of conjugates was verified by SDS-PAGE with both protein staining and carbohydrate staining. The appearance, shape, color, size, tightness, friability, mass loss during drying and ash content of zein-MS capsule shells met the requirements of the Chinese pharmacopoeia (2015 Edition).

Key words: zein, glycosylation, structural characterization, capsule shells